High conductivity polyaniline compositions and uses therefor

ABSTRACT

The present invention describes compositions formed from polyanaline and carbon nanotubes, which exhibit enhanced conductivity and which provide uses in electronic circuit applications.

FIELD OF THE INVENTION

The present invention describes compositions formed from polyanaline andcarbon nanotubes, which exhibit enhanced conductivity and provide highutility in novel applications in electronic circuits.

TECHNICAL BACKGROUND OF THE INVENTION

Conductive polymers have long been known in the art, includingpolyacetylene, polypyrrole, poly(para-phenylene), and derivativesthereof. While in some cases exhibiting metallic-like conductivity,highly conductive polymers have been limited in their practicalapplications because they are typically chemically unstable in use, andvirtually intractable, being unsuited for either solution or meltprocessing. All conductive polymers require acid or oxide functionality,usually referred to as doping, to achieve their high conductivities.

Polyaniline (PANI) stands out among conductive polymers in that it isknown in the art to be chemically stable and readily soluble inconventional, environmentally friendly solvents, and thus offers thepossibility for employing ordinary means known in the art formingcoatings, films and sheets, fibers, printed patterns, and so forth.

Conductive PANI is described in great detail in Chiang et al, SyntheticMetals, 13 (1986), pp. 193-205. Chiang et al disclose numerous PANIcompositions, identifying the protonic acid doped emeraldine nitrogenbase salt, as the most highly conductive form, with a conductivity of 5S/cm. This conductivity remains well below the 10² S/cm rangecharacteristic of certain other conductive polymers, and whichrepresents practical threshold conductivity for widespread utility inelectronics.

Levon et al, Polymer 36, pp 2733ff (1995) and Ahiskog et al, SyntheticMetals, 69, pp 135ff (1995) disclose formation of the PANI nitrogen basesalt at elevated temperature by combining with liquid organic acids suchas dodecylbenzenesulfonic acid (DBSA).

There is considerable incentive to find a way to enhance theconductivity of PANI while preserving the desirable chemical stabilityand processibility thereof. Specifically, a PANI composition exhibitinga conductivity of ca. 10² S/cm may be a highly preferred material forimportant applications in electronics.

It is known in the art to combine PANI with inorganic fillers, includingconductive fillers such as graphite, metal fibers, and superconductingceramics, see for example Jen et al, U.S. Pat. No. 5,069,820.

Carbon nanotubes are a relatively new form of matter related to C₆₀ thespherical material known popularly as “Buckminster Fullerene” While new,carbon nanotubes have elicited much interest because of their unusualstructure and are available commercially. They are described inconsiderable detail in Carbon Nanotubes and Related Structures, by PeterJ. F. Harris, Cambridge University Press, Cambridge, UK (1999).

Composites of conductive polymers and carbon nanotubes in the form offilms are disclosed in Coleman et al, Phys. Rev. B 58 (12) R7492ff(1998), Chen et al, Advanced Materials 12 (7) 522 ff (2000), and Yoshinoet al, Fullerene Sci. Tech. 7 (4) 695ff (1999).

Coleman et al, op.cit. discloses composites ofpoly(p-phenylenevinylene-co-2,5-dioctoxy-m-phenylenevinylene) (PMPV)with carbon nanotubes produced by an electric arc procedure. Massfractions of nanotubes plus residual soot ranged from ca. 0.5-35%. Filmswere spin-coated onto a platinum surface from a toluene solution.Conductivity is shown to exhibit a six order of magnitude increasebetween ca. 4% and ca 9% nanotubes.

Also disclosed in Coleman et al, op.cit., is a failed attempt to make asimilar composite with PMMA. The failure is said to result frommolecular conformational causes.

Chen et al, op.cit., disclose composite films of nanotubes andpolypyrrole. Both films and coated nanotubes are disclosed. Thenanotubes are shown to enhance the conductivity of the polypyrrole. Thefilms are deposited by exposing various substrates to a solution ofpyrrole and nanotubes followed by electropolymerization of the pyrrolein situ on the substrate, thus entrapping the nanotubes within thepolymer matrix. Chen also employs arc-grown nanotubes.

Yoshino et al, op.cit., disclose composites of poly(3-hexylthiophene)(PAT6) and nanotubes produced by chemical vapor deposition and purified.The nanotubes were dispersed in hexene and mixed with the chloroformsolution of the polymer. Films were formed by casting on a quartz plate.A ca. 4 order of magnitude change in conductivity was observed between avolume fraction of ca. 1% to ca. 10%, with the percolation thresholdestimated to be at ca. 5.9%.

Laser thermal ablation image transfer technology for color proofing andprinting is described in Ellis et al, U.S. Pat. No. 5,171,650 andelsewhere. Similar methods are in current commercial use in the printingand publishing businesses.

SUMMARY OF THE INVENTION

The present invention provides for a composition comprising a nitrogenbase salt derivative of emeraldine polyaniline and carbon nanotubes.

The present invention further provides for electronic circuitscomprising conductive pathways of a nitrogen base salt derivative ofemeraldine polyaniline and carbon nanotubes.

The present invention further provides for a process for depositingconductive pathways from a donor element onto a receiver substratecontiguous with the donor element, wherein the donor element is alayered structure comprising a support layer capable of partiallyabsorbing laser radiation, one or more heating layers, and an imagingtopcoat transfer layer, and, optionally, an ejection layer, the processcomprising:

-   -   (a) exposing said support layer to incident laser energy;    -   (b) converting said laser energy to heat in said one or more        heating layer(s) that is (are) contiguous with the topcoat that        absorbs said laser energy;    -   (c) said heat applied to said topcoat being sufficient to effect        a transfer of at least a portion of said topcoat to a receiving        surface;    -   wherein the topcoat is a conductive PANI/nanotube composite.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic of the laser deposition apparatus used to formelectronically conductive pathways on a substrate.

FIG. 2 is a pixelated image generated using computer-aided software. Theimage was translated into a pattern of pixels as further describedherein.

FIG. 3 represents an image showing a close-up of source and drains andan intervening channel.

DETAILED DESCRIPTION

The present invention describes compositions comprising polyaniline andcarbon nanotubes that exhibit electronic conductivities of ca. 10² S/cmwhile retaining the desirable chemical stability and solutionprocessibility of polyaniline. The compositions of the present inventionare highly suitable for preparation as coatings deposited insolution/dispersion form on substrates. In a preferred embodiment, theso-deposited coating is employed as a thermal image transfer medium,enabling the formation thereby of conductive pathways in electroniccircuits.

In the practice of the present invention the emeraldine form of PANI,wherein the PANI is made up of alternating units of the oxidized andreduced form of the monomer, as described in detail in Chiang et al, op.cit., is treated according to the method of Chiang et al with a protonicacid to form a nitrogen base salt. According to one method, thewater-insoluble emeraldine base is dispersed in an aqueous protonic acidsuch as HCl, followed by drying to form a conductive powder. However, itis preferred to combine the emeraldine base with a liquid organic acid,such as dodecylbenzenesulfonic acid (DBSA), to form an organic salt thatis soluble in common solvents such as toluene, xylene, and otheraromatic solvents. In order to achieve a high level of conductivity, theemeraldine base should be combined with liquid acid at a temperature of80-150° C. In the case in which the acid is in molar deficit all acidbecomes consumed in the protonation of the PANI base units and thesystem is thus composed of protonated and unprotonated PANIconstitutional units. In contrast with acid in molar excess, all PANIbase becomes protonated and the mixture is composed of the protonatedPANI and excess acid. An excess of acid promotes solubility but may havedeleterious effects on electronic properties.

One of skill in the art will appreciate that the unexpected effects andbenefits of the present invention may not be realized with everyprotonated PANI, however formed. It is found in the practice of thepresent invention that certain protonated PANI compositions are highlyeffective while others are ineffective, as shown hereinbelow in thespecific embodiments hereof.

Both single-walled and multi-walled nanotubes are known in the art, andeither is suitable for the practice of the present invention.Furthermore, the caps present at the ends of the tubes may be reduced bytreatment with oxidizing acids (Tsang et al. Nature, 372, (1994) 1355)such as nitric acid, which inevitably creates surface acid sites, whichare used to protonate the PANI. There are several methods employed inthe art for producing nanotubes. Regardless of the method employed, itis preferred that the carbon nanotubes be relatively free ofcontaminating matter. Purities of over 90% by weight are preferred.Single-walled nanotubes are preferred.

One of skill in the art will understand that the exact concentration ofnanotubes needed to achieve the requisite increase in conductivity willdepend, among other things, on the degree to which the PANI has beenconverted to the nitrogen base salt, the particular nanotubes employed,and the target conductivity. In the composition of the invention, aconcentration of nanotubes between 0.5% and 30% by weight is suitablewith a concentration between 1% and 10% preferred, with 1% to 5% mostpreferred. At concentrations below 0.5% little practical increase inconductivity is anticipated. Concentrations above 30% are expected toadversely affect the physical properties of the composite. Nanotubes areexpensive, at present; it is not desirable to employ more than theminimum number of nanotubes needed to achieve the desired enhancement ofconductivity.

It has been found satisfactory in the practice of the invention to formthe composite of the invention by dissolving the nitrogen base salt ofan organic acid such as DBSA or DNNA in an aromatic solvent such astoluene or xylene at a concentration of ca. 5-15% by weight and thenmixing the solution with a dispersion of carbon nanotubes in the same ora miscible second solvent. The concentration of nanotubes in thedispersion is ca. 0.5-10% by weight. The weight ratio of nanotubes topolymer in the composite may be controlled by simply controlling therelative amounts of the solution and dispersion employed. The dispersionof nanotubes has been found to achieve satisfactory homogeneity afterbeing subject to ultrasonic agitation for 10 to 30 minutes, preferably20 minutes at room temperature. After the nanotube dispersion andpolymer solution are combined, they are subject to ultrasonic agitationfor 2.5 to 10 minutes, preferably 5 minutes. After mixing, thedispersion so formed can then be cast onto a substrate using anyconventional method known in the art. A preferred method is to spreadthe mixture onto a substrate such as a polyester film and to use adoctor blade to produce a coating of uniform thickness. The coating isthen subject to vacuum extraction to remove the solvent, leaving behinda solid coating of the composite of the invention.

One particularly preferred use of the composite of the present inventionis as a conductive pathway in electronic circuits, said conductivepathway being produced by laser thermal transfer imaging. In laserthermal transfer imaging a donor element is used to transfer an imageonto a receiver element upon exposure of the donor element to a sequenceof laser pulses describing a pattern, which imparts to the transferredimage the desired form and resolution.

The donor element is a layered structure comprising a support layer,preferably a flexible support layer, a heating layer, and a transferlayer. In one embodiment, the support layer is sputter-coated with athin layer of metal, which in turn is solution coated with a layer ofthe PANI/NT composite of the present invention.

In use, the thin metal heating layer absorbs incident laser radiationconverting it into heat thereby causing the partial decomposition of anyorganic matter proximate to the point of laser incidence, which, inturn, propels the PANI/NT layer onto a receiver substrate. The organicmatter may include the polymeric substrate, an optional separate organic“ejection layer” specifically selected for its rapid decomposition intogaseous by-products and the PANI/NT transfer layer itself. It is thedecomposition of portions of the organic matter proximate to the heatinglayer that produces rapidly expanding gaseous low molecular weightcomponents, which provide the propulsive force to propel the adjacentportion of the PANI/NT layer to the receiving element. The laser can bescanned across the coated surface of the donor element, turned on andoff according to a preprogrammed pattern, thereby forming a highprecision image on the receiving surface.

Laser thermal ablation transfer imaging is well-known in the art ofcolor proofing and printing, as described, for example, in Ellis et al,U.S. Pat. No. 5,171,650, which is herein incorporated by reference tothe entirety. It is a completely surprising result that the method ofEllis et al can be adapted in its entirety to the production ofconductive polymer pathways by substituting the PANI/nanotube compositeof the present invention for the pigmented layer in Ellis et al. In thepresent invention, a donor element comprises a support substrate (i), alayer capable of partially absorbing a high power pulse of laserradiation and rapidly converting said absorbed laser radiation to heatwithin the confines of a sufficiently small area so as to effect thetransfer of an image of acceptable resolution onto the receiving surface(ii), an imaging topcoat (iii) essentially coextensive with saidradiation absorbing layer, said imaging topcoat (iii) comprising thehighly conductive PANI/nanotube composite of the present invention. In asecond embodiment, a specially tailored optional organic ejection layeris also included in order to enhance the speed and precision of theresponse to the laser pulse.

In the practice of the invention said radiatively absorbing layer (ii)absorbs incident laser energy, which is applied at a rate sufficient totransfer the carrier topcoat (iii) to a receiving surface, and isapplied within sufficiently narrow confines that the image formed on thereceiving surface is of sufficient resolution for the intended purpose.Resolution of 1 micrometer is readily achievable by this method.

For the laser beam to heat, the incoming radiation must be adsorbed. Theoptical absorption of the metal layer is critical. If the metal layer istoo thick it reflects the incident radiation; if it is too thin ittransmits the radiation. There is an optimum thickness for maximumabsorption of the incoming radiation. This is determined by thedielectric constant of the specific metal layer at the laser wavelength.In the practice of the invention, a thickness of ca. 10 nanometers of Nihas been found to be satisfactory.

The receiving surface is in direct and intimate contact with the imagingtopcoat of the transfer medium.

In the practice of the invention, Mylar® polyester film has been foundto be a satisfactory substrate for the laser thermal transfer medium ofthe invention. Other suitable substrates will include polyvinylchloride,polypropylene and polyethylene. There are no particular limitations onthe substrate except that they must be polymeric and transparent to theincident laser radiation.

Satisfactory results can be achieved without a separate organic ejectionlayer, utilizing only a support layer, a heating layer, and a PANI/NTtransfer layer, wherein the interface at the heating layer is partiallydecomposed to form the gaseous decomposition products necessary topropel the PANI/NT. However, a separate organic ejection layer ispreferred.

Polymers, especially polymers having a decomposition temperature belowthat of the PANI/NT composite, are preferred for use in the organicejection layer, which is preferred in the practice of the invention.Suitable polymers include polycarbonates such as polypropylenecarbonate; substituted styrene polymers such aspoly(alpha-methylstyrene); polyacrylate and polymethacrylate esters,such as polymethylmethacrylate and polybutylmethacrylate; cellulosicmaterials such as cellulose acetate butyrate and nitrocellulose;polyvinyl chloride; poly(chlorovinyl chloride); polyacetals;polyvinylidene chloride; polyurethanes with decomposition temperaturesof about 200° C.; polyesters; polyorthoesters; acrylonitrile andsubstituted acrylonitrile polymers; maleic acid resins; and copolymersof the above. Mixtures of suitable polymers can also be used. Preferredpolymers for the ejection layer are polyacrylate and polymethacrylateesters, nitrocellulose, poly(vinyl chloride) (PVC), and chlorinatedpoly(vinyl chloride) (CPVC). Most preferred are poly(vinyl chloride) andchlorinated poly(vinyl chloridelt is in some instances satisfactory toemploy the polymeric ejection layer as the support layer as well,thereby eliminating an entire layer in the structure of the donorelement; however it is preferred to use two different layers. While thebest arrangement will vary depending upon the exigencies of the specificapplication, in general the total thickness of the ejection layer andsupport layer should be in the range of 1-3 micrometers. When a separatesupport layer is employed, an ejection layer of less than 25 micrometersis satisfactory, but there needs to be enough to provide adequateablation of the PANI/NT layer (the ablated region is 0.2-0.3 microns).

Other materials can be present as additives in the ejection layer aslong as they do not interfere with the essential function of the layer.Examples of such additives include plasticizers, coating aids, flowadditives, slip agents, antihalation agents, antistatic agents,surfactants, and others that are known to be used in the formulation ofcoatings. In the embodiments of the invention wherein such additives aredesirable, it is particularly preferred that there be an ejection layerwhich is distinct from the PANI/NT composite itself.

The heating layer preferably absorbs 20-40% of the incident laserradiation, and is capable of sustaining an extremely rapid rise intemperature at the point of incidence of the laser pulse. In a preferredembodiment the heating layer is deposited on the flexible ejectionlayer. Materials suitable for the heating layer can be inorganic ororganic and can inherently absorb the laser radiation or includeadditional laser-radiation absorbing compounds. Inorganic materials arepreferred.

Suitable inorganic materials include transition metals, metals, andnon-metals, including elements of Groups IIIa, IVa, Va, VIa, VIII, IIIb,and Vb of the periodic table of elements, their alloys with each other,and their alloys with the elements of Groups Ia and IIa. Carbon is asuitable non-metal. Metals are preferred. Preferred metals include Al,Cr, Sb, Ti, Bi, Zr, Ni, In, Zn, and their oxides, suboxides and suitablealloys. More preferred are Al, Ni, Cr, Zr and C. Most preferred are Al,Ni, Cr, and Zr.

The thickness of the heating layer is generally about 20 Angstroms to0.1 micrometer, preferably about 50 Angstroms for Al and 80 Angstromsfor Cr. The specific thickness of the metal layer is chosen based onthat providing the maximum absorption at the laser wavelength.Therefore, the metal thickness is dependent on the specific dielectricconstant of each metal.

Although it is preferred to have a single heating layer, it is alsopossible to have more than one heating layer, and the different layerscan have the same or different compositions, as long as they allfunction as described above. The total thickness of all the heatinglayers should be in the range given above, i.e., 20 Angstroms to 0.1micrometer.

The heating layer(s) can be applied using any of the well-knowntechniques for providing thin metal layers, such as sputtering, chemicalvapor deposition, and electron beam deposition.

The PANI/NT composition of the present invention is deposited upon themetallic coating preferably by solution casting from toluene or xylene,applied via a Meyer rod, to a dried film thickness ranging from 0.3 to 3microns, preferably 1 micrometer.

The donor element thus formed is positioned on the receiving surface,the PANI/NT coating being directly in contact to the receiving surface.The opposite surface of the donor element is then subject to laserirradiation in a pattern of pulses, which causes the ejection of PANI/NTfrom the transfer medium and onto the receiving substrate in the desiredpattern. Suitable laser irradiation includes infrared diode laserirradiation in the wavelength range of 780 nm to 850 nm at incidentfluences of 100 mJ/cm2 to 400 mJ/cm2 delivered in a pulse of about 1microsecond duration. Incident laser fluence must be sufficiently highto effect ejection of a PANI/NT “pulse” but not so high that degradationof the PANI/NT material is initiated

Suitable receiving surfaces include polymethacrylate andpolymethacrylate co-polymer. Typical coatings of the receiver arecopolymers of methyl methacrylate, butyl methacrylate and glycidylmetacrylate, styrene and polycaprolactone coated onto a polyestersubstrate or can be free standing.

In a preferred embodiment, the patterned layer of PANI/NT is used assource and drain of a plastic transistor wherein the semiconducting,dielectric and gate will be sequentially deposit to complete thecircuit.

The present invention is further described according to the followingspecific embodiments.

EXAMPLE 1

The PANI-DBSA material was supplied by UNIAX Corporation (Santa Barbara,Calif.) in a 9% solids solution in toluene. Single wall carbonnanotubes, manufactured by pulsed laser vaporization of a metal/carbontarget in a furnace at 1100° C., were purchased from Rice University.The nanotubes were purified to greater than 90% purity by rinsing innitric acid, water and toluene. The main impurity was leftover Ni/Cocatalyst particles. The carbon nanotubes ranged between 0.2 and 2microns in length.

The nanotubes were dispersed in toluene at 1.43% by weight. The carbonnanotubes slurry was prepared by adding 0.286 g of carbon nanotubes and19.714 g of Toluene into a 2 oz container. The mix was then subject toultrasonic agitation for 20 minutes while maintaining a vortex in theslurry. Appropriate amounts of the slurry were added to the specificamount of 9% Pani/DBSA solution needed to achieve the desired nanotubesconcentration in the dry film, and the mixture subject to ultrasonicagitation for 5 minutes. The amounts of slurry and DSBA/PANI solutionswere adjusted as follows to give the desired nanotube TABLE 1 Example 1Specimens Weight of 1.43% Nanotube Weight of slurry in % Nanotubes inSpecimen 9% DSBA/PANI Toluene dry film Control 10 0 0 Specimen 1A11.0834 0.1748 0.25 Specimen 1B 11.055 0.3496 0.5 Specimen 1C 11.02770.5244 0.75 Specimen 1D 11.000 0.6993 1.00 Specimen 1E 10.972 0.87411.25 Specimen 1F 10.944 1.0489 1.50 Specimen 1G 10.916 1.2237 1.75Specimen 1H 10.888 1.3986 2.00

These dispersions were coated onto 2″×3″ glass microscope slides using a#4 Meyer rod which are well known in the art for hand coating films fromsolution and dried in air in an oven at 60° C. for 45 seconds. Thecoated area was 1″×2″ and the film thickness around 4 microns. Thicknesswas determined by optical interferometry.

A line of four 1/16″ by 3″ 4000 Å thick silver contacts 0.25″ apart weresputtered through an aluminum mask on to the thus prepared film using aDenton vacuum unit (Denton Inc. Cherry Hill, N.J.). The film resistivitywas measured using the standard 4-probe measurement technique in which acurrent is applied to the two outer contacts and the voltage across thetwo inner contacts is determined. The current was supplied by a HewlettPackard 6234A dual output power supply and was measured using anelectrometer (Keithley 617). The voltage was measured at the two innercontacts using a Keithley miltimeter. The resistivity, p, was calculatedas: $\sigma = {{1/\rho} = \frac{ixd}{V \times A}}$

Where p is the resistivity in (ohm-cm), V is the voltage measured at theinner contacts, i is the current at the 2 outer contacts, d is theseparation between the inner contacts, and A is the cross-sectional areaof the film determined from the product of the distance between theouter contacts and the film thickness. The conductivity for each film isshown in Table 2 and depicted graphically in FIG. 1. TABLE 2 Specimen NTconc σ (S/cm) Control 0 0.00018 Specimen 1A 0.25 0.00025 Specimen 1B 0.50.00017 Specimen 1C 0.75 52 Specimen 1D 1 62 Specimen 1E 1.25 62.539Specimen 1F 1.5 39 Specimen 1G 1.75 36.7 Specimen 1H 2 44

Comparative Example 1

A 2.60 wt. % solution of the conducting polyaniline use in this examplewas prepared by mixing 14.36 g mixed xylenes (EM Science, purity: 98.5%)to 0.9624 g XICP-OSO1, a developmental conductive polyaniline solutionobtained from Monsanto Company. XICP-OSO1 contains approximately 48.16wt. % xylenes, 12.62 wt. % butyl cellosolve, and 41.4 wt. % conductivepolyaniline wherein the nitrogen base salt was prepared by treating thePANI with dinonylnaphthalenic acid (DNNA).

Nanotubes were dispersed in turpinol at 1.43% by weight. Thenanotube/turpinol mixture was subject to ultrasonic agitation for 24hours at ambient temperature prior to mixing with the 41.4% solution ofXICP-OSO1. PANI-XICP-OSO1/NT dispersions were made at ratios to givenanotube/total solids concentration ratios 0, 0.25, 0.5, 0.75, 1, 1.25,1.5, 1.75, 2, 4, 6, 10, 20 and 40% were coated onto 2″×3″ glassmicroscope slides and dried in air at 60° C. for 30 seconds.

The coated area was 1″×2″. Film thickness was determined by opticalinterferometry. Silver contacts for resistivity measurements weresputtered to 4000 Å in thickness through an aluminum mask using a Dentonvacuum unit (Denton Inc. Cherry Hill, N.J.). The film resistivity wasdetermined according to the method of Example 1. The resistivity versusnanotube concentration is shown in Table 3. TABLE 3 NT conc. Specimen(%) σ (S/cm) Control 0 0.000306 Specimen CE1A 0.25 0.00048 Specimen CE1B0.5 0.0068 Specimen CE1C 0.75 0.015 Specimen CE1D 1 0.114 Specimen CE1E1.5 0.3698 Specimen CE1F 2 1.31 Specimen CE1G 2.5 1.27 Specimen CE1H 41.53 Specimen CE1I 6 1.08 Specimen CE1J 8 1.9 Specimen CE1K 10 1.87Specimen CE1L 20 3.37 Specimen CE1M 40 27.53

Example 2

Laser thermal ablation transfer was employed to create an electroniccircuit component with a PANI/nanotube composition.

A donor layer was formed by coating a 10 nanometer thick layer ofmetallic nickel onto 400D Mylar® by electron-beam deposition. The thusformed Ni layer exhibited 35% optical transmission at a wavelength of830 nm. A transfer layer was formed by coating the thus formed Ni layerwith a 1 micrometer thick layer of the composition of ComparativeExample 1 designated CE1J using a #4 Meyer rod.

The receiving layer consisted of a 1 micrometer thick layer ofpolythiophene coated onto 400D Mylar® from a 2% solids solution intoluene with a #4 Meyer rod. The coating was air dried for 30 minutes.

The image shown in FIG. 2 was generated using computer aided designsoftware. The image was translated into a pattern of pixels that weredesignated either “on” or “off” to correspond respectively to activationand deactivation of the laser to be employed for image transfer.

The images were obtained using a Spectrum CREO Trendsetter with 5080 DPIresolution (CREO-Scitex, Vancouver, Canada) equipped with a SpectrumTrendsetter Exposure Unit comprising a 20 watt infrared diode laseremitting 1 microsecond pulses at a wavelength of 830 nanometers. TheSpectrum CREO Trendsetter comprised an 81.2-cm long drum having aperimeter of 91 cm. The receiver and donor elements were loaded intoseparate cassettes, which is placed into the unit. Prior to exposure thereceiver was automatically loaded from the cassette onto the drum andheld by vacuum. The donor, slightly larger than the receiver, was thenautomatically loaded from the cassette and positioned directly on top ofthe receiver and held by vacuum at all four edges.

The pixelated image of FIG. 2 was loaded into the control computer ofthe CREO unit, and the donor was then exposed according to theprogrammed pattern with the desired pattern. To form the image, thelaser beam was split by a light valve to form an array of 240 5×2micrometer overlapping pixels. The laser head was translated along thedrum and each pixel was turned on or off to form the image. The laserfluence was adjustable 7 Watts and the drum speed was 150 RPM. The scaleof FIG. 2 is 5 cm in width and 9 cm in height. Five mm gates are shownat (2), 2 mm gates are shown at (4) and 1 mm gates are shown at (6).Twenty μ channels are shown at (8). A 1 mm wide source is shown at (10);a 2 mm wide source is shown at (12) and a 5 mm wide source is shown at(14).

After exposure the image of FIG. 2 had been transferred to the receiverin the form of a PANI/nanotube “ink”. FIG. 3 is an image showing aclose-up of a source (16), drain (18), and intervening channel (20). Thechannel (20) was 20 micrometers wide, as shown.

1-4. (canceled)
 5. A process for depositing conductive pathways from a donor element onto a receiver substrate contiguous with the donor element, wherein the donor element is a layered structure comprising a support layer, one or a plurality of heating layers capable of partially absorbing laser radiation, and an imaging topcoat transfer layer, and, optionally, an ejection layer, the process comprising: (a) exposing said support layer to incident laser energy; (b) converting said laser energy to heat in the one or plurality of heating layers contiguous with the topcoat, said heat applied to said topcoat being sufficient to effect a transfer of at least a portion of said topcoat to a receiving surface; wherein the topcoat is a conductive PANI/nanotube composite.
 6. The process of claim 5 wherein a heating layer is carbon.
 7. The process of claim 5 wherein the heating layer is a metal and is selected from the group consisting of Al, Cr, Sb, Ti, Bi, Zr, Ni, In, Zn, and their oxides, suboxides and alloys. 